"""A Scheme interpreter and its read-eval-print loop."""

import sys
import os

from scheme_classes import *
from scheme_eval_apply import *
from scheme_builtins import *
from scheme_reader import *
from scheme_forms import *
from ucb import main, trace



################
# Input/Output #
################

def read_eval_print_loop(next_line, env, interactive=False, quiet=False,
                         startup=False, load_files=(), report_errors=False):
    """Read and evaluate input until an end of file or keyboard interrupt."""
    if startup:
        for filename in load_files:
            scheme_load(filename, True, env)
    while True:
        try:
            src = next_line()
            while src.more_on_line():
                expression = scheme_read(src)
                result = scheme_eval(expression, env)
                if not quiet and result is not None:
                    print(repl_str(result))
        except (SchemeError, SyntaxError, ValueError, RuntimeError) as err:
            if report_errors:
                if isinstance(err, SyntaxError):
                    err = SchemeError(err)
                    raise err
            if (isinstance(err, RuntimeError) and
                'maximum recursion depth exceeded' not in getattr(err, 'args')[0]):
                raise
            elif isinstance(err, RuntimeError):
                print('Error: maximum recursion depth exceeded')
            else:
                print('Error:', err)
        except KeyboardInterrupt:  # <Control>-C
            if not startup:
                raise
            print()
            print('KeyboardInterrupt')
            if not interactive:
                return
        except EOFError:  # <Control>-D, etc.
            print()
            return



def create_global_frame_with_eval_apply():
    """Initialize and return a single-frame environment with built-in names."""
    env = create_global_frame()
    env.define('eval',
               BuiltinProcedure(scheme_eval, True, 'eval'))
    env.define('apply',
               BuiltinProcedure(complete_apply, True, 'apply'))
    return env



@main
def run(*argv):
    import argparse
    parser = argparse.ArgumentParser(description='CS 61A Scheme Interpreter')
    parser.add_argument('--pillow-turtle', action='store_true',
                        help='run with pillow-based turtle. This is much faster for rendering but there is no GUI')
    parser.add_argument('--turtle-save-path', default=None,
                        help='save the image to this location when done')
    parser.add_argument('-load', '-i', action='store_true',
                        help='run file interactively')
    parser.add_argument('file', nargs='?',
                        type=argparse.FileType('r'), default=None,
                        help='Scheme file to run')
    args = parser.parse_args()

    import builtins
    builtins.TK_TURTLE = not args.pillow_turtle
    builtins.TURTLE_SAVE_PATH = args.turtle_save_path
    sys.path.insert(0, '')

    next_line = buffer_input
    interactive = True
    load_files = []

    if args.file is not None:
        if args.load:
            load_files.append(getattr(args.file, 'name'))
        else:
            lines = args.file.readlines()
            def next_line():
                return buffer_lines(lines)
            interactive = False

    read_eval_print_loop(next_line, create_global_frame_with_eval_apply(),
                         startup=True, interactive=interactive,
                         load_files=load_files)
    tscheme_exitonclick()